Amazingly enough, this Andrew Moulden is a completely unrelated person to Andrew Wakefield, with his own much more sincere but correspondingly more crackpot theory for why vaccines cause autism. I think it can be well summarized as “germ theory is wrong; germs (viruses and bacteria) don’t cause diseases, foreign particles entering the body causes them”. This claim is clearly and fundamentally wrong, just like the claim about neuroplasticity that you quote. There is no value in his work.